Shaft coupling with high torsional elasticity and method of making same

ABSTRACT

An elastic shaft coupling with high torsional elasticity having segments formed by steel sheet segment plates vulcanized to an elastomeric body and in which blocking elements bridge the radial gaps of the segments of each coupling half so as to brace the plate segments against axial deformation. All of the elastomeric bodies are vulcanized to the segments or to rings from which segments are divided in a common vulcanization procedure.

FIELD OF THE INVENTION

[0001] My present invention relates to a shaft coupling with hightorsional elasticity and to a method of making such a shaft coupling.More particularly, the invention deals with high elasticity shaftcouplings for connecting a driving unit, like a diesel engine andespecially a diesel engine flywheel with a driven unit like atransmission or generator. In such cases, the diesel engine flywheel isconnected to one half of the shaft coupling while the transmission orgenerator is connected to the other coupling half.

BACKGROUND OF THE INVENTION

[0002] Elastic shaft couplings for connecting a drive unit with a drivenunit are of course known. The generally annular shaft coupling may besubdivided into segments and each of the segments can include a platesegment forming part of one of the two coupling halves and the platesegments can be connected together by an elastic material which may bebonded to the axial surfaces of the plate segments by vulcanizationthereto. The term “axial surfaces” is here used to refer to the surfacesof the segments which face in the axial direction.

[0003] Segmented shaft couplings are available in a variety ofconfigurations and these include the shaft couplings of German PatentDocument DE 36 16 232 A1 (see especially the ring arrangement 3 thereof)and the segmented coupling of German Patent Document DE 34 34 722 A1.

[0004] Segmentation of the coupling enables the coupling to be made fromsmaller components and can be used whenever one piece coupling halfplates or elastomeric members cannot be fabricated in an economicalmanner or where one piece couplings cannot be mounted in an economicalor convenient manner. They are also of advantage wherever replacement ofthe components are necessary and have been found to be useful whereverthe machine parts connected by the shaft coupling cannot be moved apartto enable replacement.

[0005] In the past it has been necessary to fabricate the metal segmentplates from relatively expensive cast steel in the same manner asflanges were formed. Furthermore, it has been required or desirable tosupport the coupling at a bearing at a hub, usually via a lateral ringto stabilize the segments during rotation of the coupling against thecentrifugal forces which tend to develop in them. Both of theseapproaches are expensive and hence prior shaft couplings of such types(see especially DE 36 16 232 A1 for such stabilization) have not beenconsidered cost effective in many applications.

OBJECTS OF THE INVENTION

[0006] It is, therefore, the principal object of the present inventionto provide an improved segmented coupling of high torsional elasticitywhich is constructed more simply and hence is more cost effective oreconomical than shaft couplings.

[0007] It is another object of the invention to provide an improvedshaft coupling which is free from drawbacks of earlier shaft couplingsystems.

[0008] Yet another object of the present invention is to provide a shaftcoupling which has high torsional elasticity, can be manufactured simplyand economically and can be used highly effectively between a drive anda driven unit, especially between a flywheel of a diesel engine and atransmission or electrical generator.

SUMMARY OF THE INVENTION

[0009] A shaft coupling with high torsional elasticity is provided inaccordance with the invention for connecting a drive with a driven unit,the shaft coupling having a first generally annular coupling halfconnectable to the drive and a second generally annular coupling halfconnectable to the driven unit, each of the coupling halves comprising aplurality of coplanar plate segments having radial gaps between them,the shaft coupling comprising elastomeric bodies between correspondingplate segments and vulcanized to juxtaposed surfaces of the platesegments, the plate segments being composed of metal sheet having atleast main surfaces of the sheet which constitute the axial surfacesthereof formed as nonmachined faces; and blocking elements at the radialgaps coupling the plate segments of each half together across therespective gap and bracing the plate segments against axial deformation.

[0010] According to the invention, the segment plates are thin metalsheet, for example steel sheet which can have a thickness preferablyranging from 1 mm to say 25 mm. At least the major surfaces of the sheetwhich form the axial surfaces of the segment plates are not machined,i.e. are not subjected to chip-removal machining.

[0011] The segment plates are coupled together by at least one blockingelement and the segment plates according to the invention are bracedagainst one another to counteract axial deformation.

[0012] An important advantage of the present invention is that the shaftcoupling can be fabricated in a highly economical manner since itsmetallic parts can be cut from thin steel metal, e.g. by stamping or inanother non-machining approach (e.g. laser beam cutting). The expression“thin sheet metal” or “thin sheet” is intended to mean that the metalsegment plates have thicknesses which are up to 50% of the wallthickness of conventional cast steel flanges or cast steel segmentplates. Since the main surfaces of the segment sheets which constitutethe axial surfaces of the segment plates are not machined by a chipremoval method the fabrication cost on the one hand is minimized and onthe other hand the segment plates are completely free from distortionwhich can result from heating effects and from internal stresses whichcannot be excluded in machining operations. The coupling of theinvention utilizing the thin segment plates is therefore not onlyeconomical but has technological advantages and eliminates the need foroperation subsequent to the stamping or punching operation with whichthe segment plates are formed.

[0013] As far as the blocking elements are concerned, they preferablyare connected to individual segment plates and connect the segmentplates of each coupling half together by overlapping the other segmentplate of the respective coupling half.

[0014] More particularly, each of the blocking elements, located at theedge with respect to the peripheral direction of a segment can extendacross the respective coupling gap to overlap the neighboring segmentplate and preferably can have a notch, recess or groove into which theother segment plate extends so that each blocking element connected toone segment plate straddles the segment plate on the other side of thegap.

[0015] Because of the blocking elements which themselves are very simpleand economical, the previously used more complex and thus expensivesystems for stabilizing the segment plates can be eliminated.

[0016] Coupling flanges of steel sheet are themselves already known inannular elastic couplings. An example can be found in the CENTAX®couplings of the present patent application owner which have beensupplied in large number for at least a decade. These elastic couplingsare comprised substantially of two concentrically arranged annularflanges with elastic rubber ring coupling elements vulcanized betweenthe flanges and bonded to them. The transfer of torque between the partsof the coupling is effected by screws or like connectors whereby oneflange at the outer diameter and the other flange at the inner diametercan be bolted to the drive unit and the driven unit, usually a flywheeland hub. The flanges in the form of one piece steel rings enable asimple and economical fabrication and guarantee, in addition highprecision and good balance for low weight and low inertial torquetransfer.

[0017] According to a further feature of the invention, the blockingelements which are located in the region of the edge of a segment andextend across the gap to straddle the neighboring segment plate andbrace each other against axial deformation are engageable with oneanother in the peripheral direction to transfer angular force from oneto the other.

[0018] By contrast with the lateral ring of a coupling of the typedescribed in German patent document DE 36 16 232 A1, supported via arotary bearing on the hub and which stabilizes the segments against thecentrifugal forces which arise, the invention provides blocking elementswhich in the peripheral direction of the coupling enable the segmentplates to interlock but also prevent axial deformation so that the plats cannot bend or buckle, relative to one another. Such blocking elementscan have very simple constructions as will be developed below.

[0019] According to a further feature of the invention, the segmentplates and the elastomeric or rubber coupling bodies are vulcanizedtogether.

[0020] In conventional segmented couplings the individual segments,formed by two segment plates and the elastomeric bodies between them,are vulcanized together. The vulcanizing tools can thus be comparativelysimple.

[0021] With the invention, however, the segments of a coupling were allformed under the same fabrication conditions so that each elastomericelement has the same quality and the same elasticity as each otherelement of the coupling and the coupling as a whole has significantlygreater homogeneity or a homogeneity which could not be achieved withearlier couplings with respect to elastic and dynamic properties. Inaccordance with this aspect of the invention, all of the segment-shapedelastomeric bodies of the coupling are vulcanized in one commonvulcanizing operation to rings of metal which are later subdivided intosegments or into segments subdivided from rings by laser cutting.

[0022] Advantageously and in accordance with a feature of the invention,each blocking element has at least two lugs forming a lug arrangement inwhich each lug is affixed to one segment plate and partly engages overthe neighboring segment plate in the peripheral direction. The blockinglugs themselves can be simple plates or sheets and thus do not have tohave any special requirements in a structural sense. The blockingelement that is comprised of two lugs may form one of a pair and bothcan be affixed to one segment plate and can straddle both sides of theneighboring segment plate in the axial direction.

[0023] However, in a preferred embodiment, the two blocking elements ofa mating pair can each be affixed to one of the two neighboring segmentplates, can span the radial gap between them and, on the oppositesegment plate can straddle the opposite axial faces. The two blockingelements may engage one another in the peripheral direction for torquetransfer purposes as soon as there has been a certain amount of yieldingof the elastic elements.

[0024] The lugs of the blocking elements can be affixed to the sameaxial side of the respective segment plates or on opposite axial sidesthereof and in accordance with a further feature of the invention, theblocking elements may be two plates affixed to one segment andstraddling the other. Any means of attachment of the blocking elementsmay be used and preferably such means can include welding, riveting,bolting, or the like. When removable bolts and nuts are used, additionalmeans can be provided, for example, pins with a clearance fit can beused to prevent rotation of the blocking elements at the edge of therespective segment.

[0025] The lugs or plates forming the blocking element may be circulararc segments and can have inner or outer peripheries which are flushwith the corresponding peripheries of the respective segment plates.

[0026] Whether the lug is placed close to the inner periphery or theouter periphery will depend on the space available, whether the surfacesof the segment plates in the region are planar or bent inwardly oroutwardly or in an axial direction, depending on the coupling design. Asa result, the blocking elements will be provided on the side of thecoupling half concerned which is opposite the force application in theradial direction.

[0027] It has been found experimentally that a coupling in accordancewith the invention is highly advantageous when it consists of only twosegments. However, this should be considered only the minimum number ofsegments which can be provided in accordance with the invention. Inpractice, the number of segments which can be provided in accordancewith the invention will depend on the load and the dimensions of thecoupling as a whole.

[0028] In the method aspects of the invention, the metallic partsforming the segment plates are initially formed in respective closedrings. The elastomeric coupling body in segment shapes are then providedbetween the annular plates vulcanized to the metal rings, whereupon thesegments are subdivided from one another in the gaps between thecoupling body segments.

[0029] In this case the vulcanization is effected in the intermediateassembly as an annular body.

[0030] Alternatively, the metal parts of the segments, namely theplates, are initially provided as closed rings, subdivided intoindividual segment plates and all of the segment plates or the couplingsare vulcanized together to the respective elastomeric segments. In bothof these methods, the closed rings initially can be formed from steelsheet and can be subdivided by means of laser beam cuttings so that atleast the mean surfaces of the sheets which form the axial faces of thesegment plates need not be machined, i.e. processed by a chip-removaloperation.

[0031] The fabrication processes are likewise relatively inexpensive andcan provided a highly uniform reproducible product at a minimum cost.

BRIEF DESCRIPTION OF THE DRAWING

[0032] The above and other objects, features, and advantages will becomemore readily apparent from the following description, reference beingmade to the accompanying drawing in which:

[0033]FIG. 1 is an axial end view of an elastic sheet coupling inaccordance with the invention;

[0034]FIG. 2 is a cross sectional view taken along the line II-II ofFIG. 1;

[0035]FIG. 3 is a radial section taken along the line III-III of FIG. 2;

[0036]FIG. 4 is an enlarged detail view of a first blocking element forpreventing relative axial movement of two mutually neighboring segments;

[0037]FIG. 5 is a cross sectional view taken along the line V-V of FIG.4;

[0038]FIG. 6 is a view similar to FIG. 4 but illustrating anotherconfiguration of a blocking element according to the invention; and

[0039]FIG. 7 is a cross sectional view taken along the line VII-VII ofFIG. 6.

SPECIFIC DESCRIPTION

[0040] As can be seen from FIG. 2, a shaft coupling in accordance withthe invention can comprise a first planar coupling flange 11 and asecond axially dished coupling flange 12 which can comprise a planarring 12 c, a frustoconical intermediate portion 12 d and a planar hubportion 12 e, between which elastomeric coupling bodies 13 arevulcanized.

[0041] The flanges 11 and 12, which can be seen to be segmented in FIGS.1 and 3, are originally formed as annular sheet steel members and areshaped by stamping or punching and subsequently subdivided by lasercutting so that neither of these flanges nor the segment plates fromwhich they are fabricated, need to be machined, especially on theirsurfaces facing in the axial direction, i.e. their respective axialfaces.

[0042] In the shaft coupling itself, the coupling flanges 11 and 12,therefore, are not present in their original circular or annular ringshapes but rather in the form of ring segments 11 a, 11 b or 12 a, 12 b.

[0043] In the embodiment shown in FIGS. 1-3, the coupling consists ofonly two somewhat semicircular segments, each of which consists of twosegment plates 11 a, 12 a or 11 b, 12 b, and a respective and generallysemicircular segmental elastomeric body vulcanized between the twosegment plates. While the illustrated coupling, therefore, has only twosuch segments, it is also possible to provide a larger number ofsegments for each coupling.

[0044] The coupling shown in FIGS. 1-3, therefore, comprises a total offour metallic flange elements which have been designated as segmentplates and the reference numeral 14 has been used to refer to segmentplates generally. Each of the segment plates 14 is comprised of anysheet metal of a quality steel, for example, a stainless steel. The term“thin” when referring to the thin sheet metal from which the segmentplates 14 are constituted is intended to mean a thickness significantlyless than the thickness of the flanges used heretofore in segmentedcouplings and preferably no greater than 50% of the thickness of suchflanges. Furthermore, differing from conventional flanges in shaftcouplings, these sheet metal flange plates are not machined or subjectedto a chip removal processing along their axial surfaces. Any cutting isconfined to the inner and outer peripheral edges and the edges of thesegment plates defining the radial gaps between the segments.

[0045] Since the segment plates are not annular and are relatively thin,the invention provides that blocking elements 15 or 16 are provided onopposite sides of the segment plates to brace the segment platesrelative to one another in the axial direction.

[0046] As can be seen from FIGS. 1-3, moreover, the blocking elements 15which may be provided between neighboring segment plates will generallytake up more space than the blocking elements 16. The blocking elements16, moreover, enable the coupling to be flatter in the axial directionand require a reduced degree of dishing of the segment plates 14 formingthe flange 12. The flange element 11 can be completely planar as hasbeen noted to allow it to be bolted or otherwise affixed directly to theflywheel of an engine.

[0047] Details of the blocking elements 15 and 16 can be seen in FIGS. 4and 5 and FIGS. 6 and 7, respectively.

[0048] The blocking elements 15 shown in FIGS. 4 and 5 are formed fromtwo mirror-symmetrical and otherwise identical flat lugs or plates 17,especially steel plates. The two lugs 17 forming one blocking element 15are coextensive and are connected by two bolts 18. The bolts 18 haveheads 18 a (FIG. 5) which can form hexagonal sockets for a hexagonal keyand threaded shafts 18 b to which locking nuts 18 c are affixed.

[0049] The lugs 17 have extensions beyond their bolted portions whichcross the radial gap between neighboring segment plates 14 and straddlethe segment plate 14 to which the lugs are not bolted, thereby bracingthe two plates 14 against axial forces. The radial gap 19 is definedbetween rounded edges 14 a and 14 b of the two neighboring flange plates14. Thus the lugs project beyond the edge 14 b of the flange plate 14 towhich they are attached and overlap the axial faces of the flange plate14 whose plate 14 a defines the other side of the radial gap 19.

[0050] The lugs 14 are practically circular arc segments and haveperipheral edges 21 which conform and are flush with the innerperipheral edge of the segment plates 14. Of course, the lugs 17 can beprovided along the outer periphery if desired, in which case the outeredges of the plates will conform to the peripheral edge of the segmentplates 14.

[0051] Since the coupling of this embodiment consists of two segments,two blocking elements 15 are provided across each of the radial gaps 19.

[0052] On the other side of the coupling, the segment plates 19 are alsobraced against one another with corresponding blocking elements or theblocking elements 16 which are of flatter configuration and which havebeen shown in greater detail in FIGS. 6 and 7.

[0053] The blocking device 16 also comprises two lugs 22. The lugs 22however differ from those of the blocking element 15 in that they arenot both attached to the same segment plate 14 but rather one isdisposed on one of the segment plates while the other is affixed to theother segment plate 14. Preferably, however, both are provided on thesame axial side.

[0054] One part of each of the lugs 22 is affixed to the respectivesegment plate 14 by screws 23 and is held from pivoting by a pin 22which has a clearance fit in a lined hole of the lug 22 and therespective segment plate 14. The lugs have projecting portions 22 whichreach across the radial gap 19 and overlie the other segment plate 14.Thus each projecting portion 22 a extends across the gap 19 defined bythe two radial edges 14 a, 14 b. This contrasts with the straddlingarrangement of the projecting portion 17 a of the lug 17 of FIGS. 4 and5. The screws 23 are countersunk screws in this embodiment to maintainthe flat configuration.

[0055] As is also visible from FIGS. 6 and 7, the edge zones of theelastomeric bodies 13 are set back by a short distance from the edges ofrespective segment plates 14 and in this setback region the blockingelement or device 16 is provided.

[0056] As noted, the lugs 22 can be provided along the outer or innerperipheries of the segment plate and in the embodiment shown in FIGS. 6and 7 are disposed along the inner periphery flush with the edge 20. Asalso can be seen from FIGS. 6 and 7, the projecting portions 22 a can beso interfitted (FIG. 6) that the segment plates 14 not only brace eachother against axial deformation but the lugs 22 can engage one anotherin the peripheral direction to transfer torque once the gap 19 hasnarrowed sufficiently.

[0057] As has been described, the metal elements of each coupling halfare initially a single ring and can be vulcanized as a ring to theelastomeric body 13 before the rings are cut through to form the gaps 19and separate the segment plates by the laser-cutting operation.

[0058] Alternatively, the ring is cut through and the elastomeric bodyis then vulcanized to the segment. In either case the vulcanization canbe effected simultaneously for all segments to ensure an optimaluniformity of the elastomeric element and their bonds to the segmentplates.

[0059] The lugs 22 need not be provided on the same axial side of thesegment plates 14 as shown in FIG. 7 but can be located on oppositesides thereof. The embodiment as shown in FIGS. 6 and 7 provide howeverthe flattest configuration of the coupling. Furthermore, the blockingelements on the two sides of the coupling need not be of differenttypes. For example the blocking elements of type 15 may be provided onboth coupling halves or, conversely, the coupling element of type 16 maybe used on both coupling halves.

[0060] In either case the coupling elements occupy space which isprovided at the segment plates in the setback region of the elastomericbody so that they do not contribute to an increased overall axialthickness of the coupling.

I claim:
 1. A shaft coupling with high torsional elasticity forconnecting a drive with a driven unit, said shaft coupling having afirst generally annular coupling half connected to said drive and asecond generally annular coupling half connected to said driven unit,each of said coupling halves comprising a plurality of coplanar platesegments having radial gaps between them, said shaft coupling comprisingelastomeric bodies between corresponding plate segments and vulcanizedto juxtaposed surfaces of said plate segments, the plate segments beingcomposed of metal sheet having at least main surfaces of the sheet whichconstitute the axial surfaces thereof formed as nonmachined faces; andblocking elements at said radial gaps coupling the plate segments ofeach half together across the respective gap and bracing the platesegments against axial deformation.
 2. The shaft coupling defined inclaim 1 wherein each of said blocking elements is connected to one ofsaid plate segments, is disposed at an edge of the respective platesegment, extends across the respective gap and engages over aneighboring plate segment.
 3. The shaft coupling defined in claim 1wherein said blocking elements are disposed at respective edges of theplate segments, extend across the respective gaps and engage aneighboring plate segment whereby the blocking elements mutually bracethe plate segments against axial deformation.
 4. The shaft couplingdefined in claim 1 wherein said plate segments are composed of steelsheet.
 5. The shaft coupling defined in claim 1 wherein all of saidelastomeric bodies are vulcanized between the respective plate segmentstogether.
 6. The shaft coupling defined in claim 1 wherein at least oneof said blocking elements comprises a pair of lugs, each of said lugsbeing affixed to one of said plate segments and reaches over aneighboring plate segment in a peripheral direction.
 7. The shaftcoupling defined in claim 6 wherein at least one of said blockingelements comprises two lugs which are affixed on opposite sides of oneof said plate segments and has projecting portions straddling theneighboring plate segment.
 8. The shaft coupling defined in claim 6wherein said lugs are affixed on the same side of a plate segment and aneighboring plate segment to reach across a radial gap between saidplate segments and axially brace said segments against one another. 9.The shaft coupling defined in claim 6 wherein said lugs are lugs areprovided on the same plate segment.
 10. The shaft coupling defined inclaim 6 wherein said lugs are provided on plate segments on oppositesides of a respective radial gap.
 11. The shaft coupling defined inclaim 6 wherein said lugs are disposed so as to peripherally engage oneanother.
 12. The shaft coupling defined in claim 6 wherein at least oneof said lugs is connected to a respective plate segment by a fastenerand is prevented from rotating by a pin transfixing said lug and therespective plate segment.
 13. The shaft coupling defined in claim 6wherein said lugs are provided along a periphery of the respective platesegments and are flush with said periphery.
 14. The shaft couplingdefined in claim 6 wherein said lugs conform to circular arc segments.15. The shaft coupling defined in claim 6 wherein said lugs arecoextensive with one another on opposite sides of a plate segment andare connected together by fasteners passing through a respective platesegment.
 16. A method of making a shaft coupling comprising the stepsof: providing two metal rings having major surfaces adapted to formaxial faces of the shaft coupling without machining; positioningelastomeric segmental bodies between said rings and vulcanizing saidsurfaces to said body; radially subdividing said rings between thebodies to form respective coupling segments; and assembling saidsegments with blocking elements at radial gaps therebetween saidblocking elements bracing the plate segments formed by subdividing saidrings against axial deformation.
 17. The method defined in claim 16wherein the rings are cut by laser beam cutting.
 18. A method of makinga shaft coupling comprising the steps of: providing two metal ringshaving major surfaces adapted to form axial faces of the shaft couplingwithout machining; subdividing said rings into individual segmentplates; for all of the segment plates of a coupling, vulcanizing betweenpairs of said segment plates to form respective segments, respectiveelastomeric coupling bodies in common; and assembling said segments withblocking elements at radial gaps therebetween said blocking elementsbracing the plate segments formed by subdividing said rings againstaxial deformation.
 19. The method defined in claim 18 wherein thecutting is effected by laser beam cutting.